1. Field of the Invention
This invention relates to the art of diaphragms for pumps and the like in which the flexing stresses are controlled to provide long wear life and withstand high pressures. Specifically, the invention deals with a one-piece molded plastics material membrane or diaphragm disks for pumps, compressors and the like which has a flat planar end face confronting the media being pumped or compressed, an outer peripheral clamping area, an intermediate annular flexible bending zone adjacent the clamping area, and a central thickened rigid work zone with the annular flexible bending zone increasing in thickness between the clamping area and zone.
2. Prior Art
Pump diaphragms having thickened central work portions projecting from both of sides of a flexible zone to provide stability have been successfully employed particularly in pumps for abrasive fluids in order to separate the pump piston from these fluids. A hydraulic drive system including a liquid column under pressure moved by a piston serves to flex the diaphragm which is clamped around its periphery and which is mounted to move from a back seating position into a front seating position in housing recesses that cause the diaphragm to oscillate through its free flat condition into stretched positions on both sides of the clamped periphery. The hydraulic drive system has also been replaced with a mechanical tappet type drive or direct piston drive.
Such membranes or diaphragms are exposed to great stresses and have a short useful life since even after a short time damage occurs in the intermediate bending zone which is subject to an alternate load due to the oscillation on both sides of the flat neutral free stage. The short useful life of such diaphragms presents a troublesome service problem requiring replacement of the diaphragm or pump.
The same short wear life problem exists with diaphragms which are designed flat and are not even exposed to high stresses. For example, in German Pat. No. 2,742,139 a diaphragm guidance zone is provided in the pump adjacent the clamping zone so that pressure and flexing stresses do not occur at the same location. These constructions require additional structural space to provide the outer and inner guidance zone so that the components accepting this type of diaphragm must be relatively large in diameter.
While it is possible to dimension the bending zone of a diaphragm in such a manner as to resist stresses, excess material is required and the bending behaviour of the diaphragm is such that the pump capacity is very poor.
It would be an improvement in the art to provide a diaphragm for high pressure pumps, compressors and the like which exhibits a significantly higher useful life than previously available diaphragm and minimizes flexible or stretching without decreasing pumping volume.